Power Store would be the quickest to implement.
Power Store is a prebuilt application that includes the product catalog, search, shopping cart and other features.
eCart is a tool that you can use to add a Shopping Cart and checkout to an existing catalog.
you would use Data Bridge to create the catalog display, then add eCart to the Data Assist pages to add the shopping cart.
Think in terms of buying a house that is already built versus building one yourself.